Maybe a stupid memory question...

Discussion in 'Mac Help/Tips' started by mueng, Jun 19, 2002.

  1. mueng macrumors member

    Joined:
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    Michigan
    #1
    Awhile ago I bulked up my iMac DV+ with ram. I think I remember it being PC 133, but I'm not sure, which is the problem.

    Now I'm taking it out of my iMac and putting it into my Quicksilver 2002 which requires PC133. But I am not sure if the memory from the iMac is PC 133.

    So if the memory was PC100, then the G4 just wouldn't recognize it? Any negative effects if it were PC100 and not the PC 133 memory that the G4 requires?

    Thanks
     
  2. Hemingray macrumors 68030

    Hemingray

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    #2
    It would recognize the PC100 RAM, but it will drag all your memory speed down to PC 100. I strongly recommend NOT doing that. Putting PC133 RAM in a PC100 computer is fine. But putting PC100 RAM in a PC133 computer is not good. Play it safe and just buy a PC133 chip for your G4.

    P.S. To find out if your iMac's RAM is PC100 or PC133, just check the iMac's System Profiler and see what you have in your DIMM slots.
     
  3. AlphaTech macrumors 601

    AlphaTech

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    Natick, MA
    #3
    If the memory is PC100, it will not function in the system that requires PC133 (the QS02). If there is other memory inside your system, it will show as not compatible.

    IF you put PC133 onto a system that uses PC100, then the PC133 will clock down to PC100. You can be faster memory into a slower system but not slower memory into a faster system.

    The memory should say if it is PC100 or PC133 right on the chip. Depending on where you purchased it, and what brand memory it is.
     
  4. alex_ant macrumors 68020

    alex_ant

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    #4
    How does that work - will it actually throttle down the FSB to 100MHz when using PC100 memory?

    I had a generic 10ns PC66 SDRAM DIMM installed on a PC motherboard with a 100MHz FSB (which is supposed to require PC100 memory) once, no problems. That doesn't always work, though - I got lucky. The safe thing to do would be to buy PC133 RAM, but you could try installing the PC100 RAM and staying with that if there are no mysterious crashes or system errors. Keep in mind, though, that if your system ever begins behaving strangely, the RAM is a likely culprit.

    Alex
     
  5. Hemingray macrumors 68030

    Hemingray

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    #5
    It's basically just acting as a bottleneck. It can only run as fast as its slowest component. In this case, the PC100 RAM.

    And I did put PC66 RAM in my PC100 G4 a while back before I knew anything about different types of RAM... and I don't think my computer's ever been the same since. (And yes, I took out the RAM. :p )
     
  6. alex_ant macrumors 68020

    alex_ant

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    #6
    But the machine doesn't adjust the speed of the FSB automatically to accomodate the slow RAM. It will try to run the FSB at 133MHz no matter what type of RAM is installed. The RAM will run at 133MHz too, no matter what type it is, but unless it is certified PC133, it probably won't be able to handle the higher speed, and will crash the system. But one could get lucky. :)

    Alex
     
  7. mueng thread starter macrumors member

    Joined:
    May 20, 2002
    Location:
    Michigan
    #7
    The memory I had was ordered through my college's computer store. I looked all over it for any markings of what kind it was, but there is nothing. No brand, no "PC133" or whatever.

    I took the plunge and installed it into my computer after just a comparing the existing memory with it. I already had 768 mb installed. I ran the hardware test first and it found no problems. Then I was in X and looked at "About this Mac" and the computer thinks there is 1 GB of ram (as the questionable memory is 256 mb)

    Then I went to system profiler and it seems to recognize all three slots.

    Oh yeah and I've been using the computer for a few hours now and it hasn't crashed. Nor has there been noticable speed decrease.

    So I guess it was PC133, but I guess only time will tell.

    Thanks
     

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